Due to their unique mechanical, thermal, and electrical properties, discrete fillers, including functionalized nanotubes, discrete carbon fibers, multi-walled nanotubes, ceramic powders, metallic nanoparticles, silicates, or single-walled carbon nanotubes, could be used for making polymeric nanocomposite materials with exceptional properties.
For example, if such fillers improved the flammability properties of polymers, they would provide an alternative to conventional flame retardants. The flame retardant (FR) effectiveness of clay-polymer-nanocomposites with various resins has been demonstrated (see, e.g., Giannelis, E., Adv. Mater. 1996, 8(1), 29; Gilman, J. W.; Kashiwagi, T., SMAPE J. 1997; 33(4), 40; Gilman, J. W., Applied Clay Sci. 1999; 15, 31; Zhu, J.; Morgan, A. B.; Lamelas J.; Wilkie, C. A., Chem. Mater. 2001; 13, 3774; Zanetti, M.; Camino, G.; Mulhaupt, R., Polym. Degrad. Stability, 2001; 74, 413; Gilman, J. W.; Jackson C. L.; Morgan, A. B.; Harris, R. Jr.; Manias, e.; Giannelis, E. P.; Wuthernow, M.; Hilton, D.; Phillips, S. H., Chem. Mater. 2000; 12, 1866). Similarly, the FR effectiveness in poly(methyl methacrylate) (“PMMA”) of nanoscale silica particles (average diameter of 12 nm) has also been disclosed (Kashiwagi, T., Morgan, A. B., Antonoucci, J. M., VanLandingham, M. R., Harris, R. H., Awad, W. H. and Shields, J. R., Thermal and Flammability Properties of a Silica-PMMA Nanocomposite, J. Appl. Poly. Sci. Vol. 89, No. 8, 2072-2078, 2003). Likewise, multi-walled carbon nanotube/poly(propylene) composites made by shear mixing method showed a significant increase in decomposition temperature due to presence of the nanotubes (Kashiwagi, T.; Grulke, E.; Hilding, J.; Harris, R.; Awad, W.; Douglas, J. Macromol. Rapid Commun. 2002, 23, 761), and multi-walled carbon nanotubes have also been studied in ethylene vinyl acetate (Beyer, G., Fire Mater., 2002; 26, 291).
Single-walled carbon nanotubes (“SWNTs”) possess a unique combination of strength, high modulus of elasticity, and excellent heat and electrical conductivity. However, SWNTs are prone to aggregation (“bundling”) due to Van der Waals attraction among the tubes, which have large surface areas. Adequate dispersion is a key factor in composite performance, and many previous attempts to uniformly disperse SWNTs throughout a polymer matrix have been less than fully successful.
It has now been discovered that a flame retardant composite can be made from SWNTs uniformly dispersed throughout a polymer matrix to form a composite.